[Kraeror]

Here you are, it should works:

PHP Code:

CMD:factionon(playerid, params[])
{
    new str[128], DUTY_STR[24], COLOR, counter = 0;
    SendClientMessage(playerid, -1, " - Online members - ");
    if((pInfo[playerid][pRank] < 1)) return SendClientMessage(playerid, -1, "You are not from any faction");
    for(new i = 0; i < MAX_PLAYERS; i++)
    {
        if(IsPlayerConnected(i))
        {
            if(pInfo[i][pFaction] == pInfo[playerid][pFaction])
            {
                if(!pInfo[i][pFactionDuty])
                {
                    DUTY_STR = "Off Duty";
                    COLOR = COLOR_WHITE;
                }
                else
                {
                    DUTY_STR = "ON DUTY";
                    COLOR = COLOR_RED;
                }
                format(str, sizeof(str),"%s: %s - %s",  GetRankName(i), PlayerName(i), DUTY_STR);
                counter++;
            }
        }
    }
    SendClientMessage(playerid, COLOR, str);
    return 1;
} 


I don't recommend to put SCM into a loop! And check the difference between this code and yours!